63 ideas
13466 | We are all post-Kantians, because he set the current agenda for philosophy [Hart,WD] |
Full Idea: We are all post-Kantians, ...because Kant set an agenda for philosophy that we are still working through. | |
From: William D. Hart (The Evolution of Logic [2010], 2) | |
A reaction: Hart says that the main agenda is set by Kant's desire to defend the principle of sufficient reason against Hume's attack on causation. I would take it more generally to be the assessment of metaphysics, and of a priori knowledge. |
13477 | The problems are the monuments of philosophy [Hart,WD] |
Full Idea: The real monuments of philosophy are its problems. | |
From: William D. Hart (The Evolution of Logic [2010], 2) | |
A reaction: Presumably he means '....rather than its solutions'. No other subject would be very happy with that sort of claim. Compare Idea 8243. A complaint against analytic philosophy is that it has achieved no consensus at all. |
13515 | To study abstract problems, some knowledge of set theory is essential [Hart,WD] |
Full Idea: By now, no education in abstract pursuits is adequate without some familiarity with sets. | |
From: William D. Hart (The Evolution of Logic [2010], 10) | |
A reaction: A heart-sinking observation for those who aspire to study metaphysics and modality. The question is, what will count as 'some' familiarity? Are only professional logicians now allowed to be proper philosophers? |
13469 | Tarski showed how we could have a correspondence theory of truth, without using 'facts' [Hart,WD] |
Full Idea: It is an ancient and honourable view that truth is correspondence to fact; Tarski showed us how to do without facts here. | |
From: William D. Hart (The Evolution of Logic [2010], 2) | |
A reaction: This is a very interesting spin on Tarski, who certainly seems to endorse the correspondence theory, even while apparently inventing a new 'semantic' theory of truth. It is controversial how far Tarski's theory really is a 'correspondence' theory. |
13504 | Truth for sentences is satisfaction of formulae; for sentences, either all sequences satisfy it (true) or none do [Hart,WD] |
Full Idea: We explain truth for sentences in terms of satisfaction of formulae. The crux here is that for a sentence, either all sequences satisfy it or none do (with no middle ground). For formulae, some sequences may satisfy it and others not. | |
From: William D. Hart (The Evolution of Logic [2010], 4) | |
A reaction: This is the hardest part of Tarski's theory of truth to grasp. |
13503 | A first-order language has an infinity of T-sentences, which cannot add up to a definition of truth [Hart,WD] |
Full Idea: In any first-order language, there are infinitely many T-sentences. Since definitions should be finite, the agglomeration of all the T-sentences is not a definition of truth. | |
From: William D. Hart (The Evolution of Logic [2010], 4) | |
A reaction: This may be a warning shot aimed at Davidson's extensive use of Tarski's formal account in his own views on meaning in natural language. |
13500 | Conditional Proof: infer a conditional, if the consequent can be deduced from the antecedent [Hart,WD] |
Full Idea: A 'conditional proof' licenses inferences to a conditional from a deduction of its consequent from its antecedent. | |
From: William D. Hart (The Evolution of Logic [2010], 4) | |
A reaction: That is, a proof can be enshrined in an arrow. |
13502 | ∃y... is read as 'There exists an individual, call it y, such that...', and not 'There exists a y such that...' [Hart,WD] |
Full Idea: When a quantifier is attached to a variable, as in '∃(y)....', then it should be read as 'There exists an individual, call it y, such that....'. One should not read it as 'There exists a y such that...', which would attach predicate to quantifier. | |
From: William D. Hart (The Evolution of Logic [2010], 4) | |
A reaction: The point is to make clear that in classical logic the predicates attach to the objects, and not to some formal component like a quantifier. |
13456 | Set theory articulates the concept of order (through relations) [Hart,WD] |
Full Idea: It is set theory, and more specifically the theory of relations, that articulates order. | |
From: William D. Hart (The Evolution of Logic [2010]) | |
A reaction: It would seem that we mainly need set theory in order to talk accurately about order, and about infinity. The two come together in the study of the ordinal numbers. |
13497 | Nowadays ZFC and NBG are the set theories; types are dead, and NF is only useful for the whole universe [Hart,WD] |
Full Idea: The theory of types is a thing of the past. There is now nothing to choose between ZFC and NBG (Neumann-Bernays-Gödel). NF (Quine's) is a more specialized taste, but is a place to look if you want the universe. | |
From: William D. Hart (The Evolution of Logic [2010], 3) |
13443 | ∈ relates across layers, while ⊆ relates within layers [Hart,WD] |
Full Idea: ∈ relates across layers (Plato is a member of his unit set and the set of people), while ⊆ relates within layers (the singleton of Plato is a subset of the set of people). This distinction only became clear in the 19th century. | |
From: William D. Hart (The Evolution of Logic [2010], 1) | |
A reaction: Getting these two clear may be the most important distinction needed to understand how set theory works. |
13442 | Without the empty set we could not form a∩b without checking that a and b meet [Hart,WD] |
Full Idea: Without the empty set, disjoint sets would have no intersection, and we could not form a∩b without checking that a and b meet. This is an example of the utility of the empty set. | |
From: William D. Hart (The Evolution of Logic [2010], 1) | |
A reaction: A novice might plausibly ask why there should be an intersection for every pair of sets, if they have nothing in common except for containing this little puff of nothingness. But then what do novices know? |
13493 | In the modern view, foundation is the heart of the way to do set theory [Hart,WD] |
Full Idea: In the second half of the twentieth century there emerged the opinion that foundation is the heart of the way to do set theory. | |
From: William D. Hart (The Evolution of Logic [2010], 3) | |
A reaction: It is foundation which is the central axiom of the iterative conception of sets, where each level of sets is built on previous levels, and they are all 'well-founded'. |
13495 | Foundation Axiom: an nonempty set has a member disjoint from it [Hart,WD] |
Full Idea: The usual statement of Foundation is that any nonempty set has a member disjoint from it. This phrasing is ordinal-free and closer to the primitives of ZFC. | |
From: William D. Hart (The Evolution of Logic [2010], 3) |
13461 | We can choose from finite and evident sets, but not from infinite opaque ones [Hart,WD] |
Full Idea: When a set is finite, we can prove it has a choice function (∀x x∈A → f(x)∈A), but we need an axiom when A is infinite and the members opaque. From infinite shoes we can pick a left one, but from socks we need the axiom of choice. | |
From: William D. Hart (The Evolution of Logic [2010], 1) | |
A reaction: The socks example in from Russell 1919:126. |
13462 | With the Axiom of Choice every set can be well-ordered [Hart,WD] |
Full Idea: It follows from the Axiom of Choice that every set can be well-ordered. | |
From: William D. Hart (The Evolution of Logic [2010], 1) | |
A reaction: For 'well-ordered' see Idea 13460. Every set can be ordered with a least member. |
13516 | If we accept that V=L, it seems to settle all the open questions of set theory [Hart,WD] |
Full Idea: It has been said (by Burt Dreben) that the only reason set theorists do not generally buy the view that V = L is that it would put them out of business by settling their open questions. | |
From: William D. Hart (The Evolution of Logic [2010], 10) | |
A reaction: Hart says V=L breaks with the interative conception of sets at level ω+1, which is countable is the constructible view, but has continuum many in the cumulative (iterative) hierarch. The constructible V=L view is anti-platonist. |
13441 | Naïve set theory has trouble with comprehension, the claim that every predicate has an extension [Hart,WD] |
Full Idea: 'Comprehension' is the assumption that every predicate has an extension. Naïve set theory is the theory whose axioms are extensionality and comprehension, and comprehension is thought to be its naivety. | |
From: William D. Hart (The Evolution of Logic [2010], 1) | |
A reaction: This doesn't, of course, mean that there couldn't be a more modest version of comprehension. The notorious difficulty come with the discovery of self-referring predicates which can't possibly have extensions. |
13494 | The iterative conception may not be necessary, and may have fixed points or infinitely descending chains [Hart,WD] |
Full Idea: That the iterative sets suffice for most of ZFC does not show they are necessary, nor is it evident that the set of operations has no fixed points (as 0 is a fixed point for square-of), and no infinitely descending chains (like negative integers). | |
From: William D. Hart (The Evolution of Logic [2010], 3) | |
A reaction: People don't seem to worry that they aren't 'necessary', and further measures are possible to block infinitely descending chains. |
13457 | A 'partial ordering' is irreflexive and transitive; the sets are ordered, but not the subsets [Hart,WD] |
Full Idea: We say that a binary relation R 'partially orders' a field A just in case R is irreflexive (so that nothing bears R to itself) and transitive. When the set is {a,b}, its subsets {a} and {b} are incomparable in a partial ordering. | |
From: William D. Hart (The Evolution of Logic [2010], 1) |
13458 | A partial ordering becomes 'total' if any two members of its field are comparable [Hart,WD] |
Full Idea: A partial ordering is a 'total ordering' just in case any two members of its field are comparable, that is, either a is R to b, or b is R to a, or a is b. | |
From: William D. Hart (The Evolution of Logic [2010], 1) | |
A reaction: See Idea 13457 for 'partial ordering'. The three conditions are known as the 'trichotomy' condition. |
13490 | Von Neumann defines α<β as α∈β [Hart,WD] |
Full Idea: One of the glories of Von Neumann's theory of numbers is to define α < β to mean that α ∈ β. | |
From: William D. Hart (The Evolution of Logic [2010], 3) |
13460 | 'Well-ordering' must have a least member, so it does the natural numbers but not the integers [Hart,WD] |
Full Idea: A total order 'well-orders' its field just in case any nonempty subset B of its field has an R-least member, that is, there is a b in B such that for any a in B different from b, b bears R to a. So less-than well-orders natural numbers, but not integers. | |
From: William D. Hart (The Evolution of Logic [2010], 1) | |
A reaction: The natural numbers have a starting point, but the integers are infinite in both directions. In plain English, an order is 'well-ordered' if there is a starting point. |
13481 | Maybe sets should be rethought in terms of the even more basic categories [Hart,WD] |
Full Idea: Some have claimed that sets should be rethought in terms of still more basic things, categories. | |
From: William D. Hart (The Evolution of Logic [2010], 2) | |
A reaction: [He cites F.William Lawvere 1966] It appears to the the context of foundations for mathematics that he has in mind. |
13506 | The universal quantifier can't really mean 'all', because there is no universal set [Hart,WD] |
Full Idea: All the main set theories deny that there is a set of which everything is a member. No interpretation has a domain with everything in it. So the universal quantifier never gets to mean everything all at once; 'all' does not mean all. | |
From: William D. Hart (The Evolution of Logic [2010], 4) | |
A reaction: Could you have an 'uncompleted' universal set, in the spirit of uncompleted infinities? In ordinary English we can talk about 'absolutely everything' - we just can't define a set of everything. Must we 'define' our domain? |
13513 | Models are ways the world might be from a first-order point of view [Hart,WD] |
Full Idea: Models are ways the world might be from a first-order point of view. | |
From: William D. Hart (The Evolution of Logic [2010], 9) |
13505 | Model theory studies how set theory can model sets of sentences [Hart,WD] |
Full Idea: Modern model theory investigates which set theoretic structures are models for which collections of sentences. | |
From: William D. Hart (The Evolution of Logic [2010], 4) | |
A reaction: So first you must choose your set theory (see Idea 13497). Then you presumably look at how to formalise sentences, and then look at the really tricky ones, many of which will involve various degrees of infinity. |
13511 | Model theory is mostly confined to first-order theories [Hart,WD] |
Full Idea: There is no developed methematics of models for second-order theories, so for the most part, model theory is about models for first-order theories. | |
From: William D. Hart (The Evolution of Logic [2010], 9) |
13512 | Modern model theory begins with the proof of Los's Conjecture in 1962 [Hart,WD] |
Full Idea: The beginning of modern model theory was when Morley proved Los's Conjecture in 1962 - that a complete theory in a countable language categorical in one uncountable cardinal is categorical in all. | |
From: William D. Hart (The Evolution of Logic [2010], 9) |
13496 | First-order logic is 'compact': consequences of a set are consequences of a finite subset [Hart,WD] |
Full Idea: First-order logic is 'compact', which means that any logical consequence of a set (finite or infinite) of first-order sentences is a logical consequence of a finite subset of those sentences. | |
From: William D. Hart (The Evolution of Logic [2010], 3) |
13484 | Berry's Paradox: we succeed in referring to a number, with a term which says we can't do that [Hart,WD] |
Full Idea: Berry's Paradox: by the least number principle 'the least number denoted by no description of fewer than 79 letters' exists, but we just referred to it using a description of 77 letters. | |
From: William D. Hart (The Evolution of Logic [2010], 3) | |
A reaction: I struggle with this. If I refer to 'an object to which no human being could possibly refer', have I just referred to something? Graham Priest likes this sort of idea. |
13482 | The Burali-Forti paradox is a crisis for Cantor's ordinals [Hart,WD] |
Full Idea: The Burali-Forti Paradox was a crisis for Cantor's theory of ordinal numbers. | |
From: William D. Hart (The Evolution of Logic [2010], 3) |
13507 | The machinery used to solve the Liar can be rejigged to produce a new Liar [Hart,WD] |
Full Idea: In effect, the machinery introduced to solve the liar can always be rejigged to yield another version the liar. | |
From: William D. Hart (The Evolution of Logic [2010], 4) | |
A reaction: [He cites Hans Herzberger 1980-81] The machinery is Tarski's device of only talking about sentences of a language by using a 'metalanguage'. |
13459 | The less-than relation < well-orders, and partially orders, and totally orders the ordinal numbers [Hart,WD] |
Full Idea: We can show (using the axiom of choice) that the less-than relation, <, well-orders the ordinals, ...and that it partially orders the ordinals, ...and that it totally orders the ordinals. | |
From: William D. Hart (The Evolution of Logic [2010], 1) |
13463 | There are at least as many infinite cardinals as transfinite ordinals (because they will map) [Hart,WD] |
Full Idea: Since we can map the transfinite ordinals one-one into the infinite cardinals, there are at least as many infinite cardinals as transfinite ordinals. | |
From: William D. Hart (The Evolution of Logic [2010], 1) |
13491 | The axiom of infinity with separation gives a least limit ordinal ω [Hart,WD] |
Full Idea: The axiom of infinity with separation yields a least limit ordinal, which is called ω. | |
From: William D. Hart (The Evolution of Logic [2010], 3) |
13492 | Von Neumann's ordinals generalise into the transfinite better, because Zermelo's ω is a singleton [Hart,WD] |
Full Idea: It is easier to generalize von Neumann's finite ordinals into the transfinite. All Zermelo's nonzero finite ordinals are singletons, but if ω were a singleton it is hard to see how if could fail to be the successor of its member and so not a limit. | |
From: William D. Hart (The Evolution of Logic [2010], 3) |
13446 | 19th century arithmetization of analysis isolated the real numbers from geometry [Hart,WD] |
Full Idea: The real numbers were not isolated from geometry until the arithmetization of analysis during the nineteenth century. | |
From: William D. Hart (The Evolution of Logic [2010], 1) |
13509 | We can establish truths about infinite numbers by means of induction [Hart,WD] |
Full Idea: Mathematical induction is a way to establish truths about the infinity of natural numbers by a finite proof. | |
From: William D. Hart (The Evolution of Logic [2010], 5) | |
A reaction: If there are truths about infinities, it is very tempting to infer that the infinities must therefore 'exist'. A nice, and large, question in philosophy is whether there can be truths without corresponding implications of existence. |
13474 | Euclid has a unique parallel, spherical geometry has none, and saddle geometry has several [Hart,WD] |
Full Idea: There is a familiar comparison between Euclid (unique parallel) and 'spherical' geometry (no parallel) and 'saddle' geometry (several parallels). | |
From: William D. Hart (The Evolution of Logic [2010], 2) |
1635 | Mathematics reduces to set theory (which is a bit vague and unobvious), but not to logic proper [Quine] |
Full Idea: Mathematics reduces only to set theory, and not to logic proper… but set theory cannot claim the same firmness and obviousness as logic. | |
From: Willard Quine (Epistemology Naturalized [1968], p.69-70) |
13471 | Mathematics makes existence claims, but philosophers usually say those are never analytic [Hart,WD] |
Full Idea: The thesis that no existence proposition is analytic is one of the few constants in philosophical consciences, but there are many existence claims in mathematics, such as the infinity of primes, five regular solids, and certain undecidable propositions. | |
From: William D. Hart (The Evolution of Logic [2010], 2) |
23634 | Accepting the existence of anything presupposes the notion of existence [Reid] |
Full Idea: The belief of the existence of anything seems to suppose a notion of existence - a notion too abstract, perhaps, to enter into the mind of an infant. | |
From: Thomas Reid (Essays on Intellectual Powers 2: Senses [1785], 05) | |
A reaction: But even a small infant has to cope with the experience of waking up from a dream. I don't see how existence can be anything other than a primitive concept in any system of ontology. |
13488 | Mass words do not have plurals, or numerical adjectives, or use 'fewer' [Hart,WD] |
Full Idea: Jespersen calls a noun a mass word when it has no plural, does not take numerical adjectives, and does not take 'fewer'. | |
From: William D. Hart (The Evolution of Logic [2010], 3) | |
A reaction: Jespersen was a great linguistics expert. |
13480 | Fregean self-evidence is an intrinsic property of basic truths, rules and definitions [Hart,WD] |
Full Idea: The conception of Frege is that self-evidence is an intrinsic property of the basic truths, rules, and thoughts expressed by definitions. | |
From: William D. Hart (The Evolution of Logic [2010], p.350) | |
A reaction: The problem is always that what appears to be self-evident may turn out to be wrong. Presumably the effort of arriving at a definition ought to clarify and support the self-evident ingredient. |
23635 | Truths are self-evident to sensible persons who understand them clearly without prejudice [Reid] |
Full Idea: Self-evident propositions are those which appear evident to every man of sound understanding who apprehends the meaning of them distinctly, and attends to them without prejudice. | |
From: Thomas Reid (Essays on Intellectual Powers 2: Senses [1785], 10) | |
A reaction: I suspect that there are some truths which are self-evident to dogs. There are also truths which are self-evident to experts, but not to ordinary persons of good understanding. Self-evidence is somewhat contextual. Self-evidence can be empirical. |
13476 | The failure of key assumptions in geometry, mereology and set theory throw doubt on the a priori [Hart,WD] |
Full Idea: In the case of the parallels postulate, Euclid's fifth axiom (the whole is greater than the part), and comprehension, saying was believing for a while, but what was said was false. This should make a shrewd philosopher sceptical about a priori knowledge. | |
From: William D. Hart (The Evolution of Logic [2010], 2) | |
A reaction: Euclid's fifth is challenged by infinite numbers, and comprehension is challenged by Russell's paradox. I can't see a defender of the a priori being greatly worried about these cases. No one ever said we would be right - in doing arithmetic, for example. |
7631 | Sensation is not committed to any external object, but perception is [Reid] |
Full Idea: Sensation, by itself, implies neither the conception nor belief of any external object. ...Perception implies a conviction and belief of something external. ...Things so different in their nature ought to be distinguished. | |
From: Thomas Reid (Essays on Intellectual Powers 2: Senses [1785], II.16), quoted by Barry Maund - Perception | |
A reaction: Maund sees this as the origin of the two-stage view of perception, followed by Chisholm, Evans, Dretske and Lowe. It implies that 'looks', 'tastes', 'sounds' etc. are ambiguous words, having either phenomenal or realist meanings. I like it. |
23637 | Primary qualities are the object of mathematics [Reid] |
Full Idea: The primary qualities are the object of the mathematical sciences. | |
From: Thomas Reid (Essays on Intellectual Powers 2: Senses [1785], 17) | |
A reaction: He spells out this crucial point, which is not so obvious in Locke. The sciences totally rely on the primary qualities, so it is ridiculous to reject the distinction (which Reid accepts). |
23638 | Secondary qualities conjure up, and are confused with, the sensations which produce them [Reid] |
Full Idea: The thought of a secondary quality always carries us back to the sensation which it produces.We give the same name to both, and are apt to confound them. | |
From: Thomas Reid (Essays on Intellectual Powers 2: Senses [1785], 17) | |
A reaction: 'Redness', for example. Reid puts the point very nicely. Secondary qualities are not entirely mental; they pick out features of the world, but are much harder to understand than the primary qualities. The qualia question lurks. |
23639 | It is unclear whether a toothache is in the mind or in the tooth, but the word has a single meaning [Reid] |
Full Idea: If it be made a question whether the toothache be in the mind that feels it, or in tooth that is affected, much might be said on both sides, while it is not observed that the word has two meanings. | |
From: Thomas Reid (Essays on Intellectual Powers 2: Senses [1785], 18) | |
A reaction: I'm glad Reid was struck by the weird phenomenon of the brain apparently 'projecting' a pain into a tooth. Presumably before the brain's role was known, people were unaware of this puzzle. There certainly are not two distinct experiences. |
6492 | Reid is seen as the main direct realist of the eighteenth century [Reid, by Robinson,H] |
Full Idea: Reid is often represented by modern opponents of the empiricists as the outstanding protagonist of direct or naïve realism and common sense in the eighteenth century. | |
From: report of Thomas Reid (Essays on Intellectual Powers 2: Senses [1785]) by Howard Robinson - Perception 1.6 | |
A reaction: Robinson does not deny that this is Reid's view. Keith Lehrer is a great fan of Reid. Personally I think direct realism is quite clearly false, so I find myself losing interest in Reid's so-called 'common sense'. |
23641 | People dislike believing without evidence, and try to avoid it [Reid] |
Full Idea: To believe without evidence is a weakness which every man is concerned to avoid, and which every man wishes to avoid. | |
From: Thomas Reid (Essays on Intellectual Powers 2: Senses [1785], 20) | |
A reaction: It seems to be very common, though, for people to believe things on incredibly flimsy evidence, if they find the belief appealing. This is close to Clifford's Principle, but not quite as dogmatic. |
23642 | If non-rational evidence reaches us, it is reason which then makes use of it [Reid] |
Full Idea: If Nature gives us information of things that concern us, by other means that by reasoning, reason itself will direct us to receive that information with thankfulness, and to make the best use of it. | |
From: Thomas Reid (Essays on Intellectual Powers 2: Senses [1785], 20) | |
A reaction: This is more of a claim than an argument, but it is hard to see how anything could even be seen as evidence if some sort of rational judgement has not been made. The clever detective sees which facts are evidence. |
7627 | You can't reduce epistemology to psychology, because that presupposes epistemology [Maund on Quine] |
Full Idea: There is something seriously misguided about Quine's project of reducing epistemology to psychology, since psychology, like any of the natural sciences, presupposes an epistemology. | |
From: comment on Willard Quine (Epistemology Naturalized [1968]) by Barry Maund - Perception Ch.1 | |
A reaction: I wonder if epistemology presupposes psychology? Belief, for example, is a category of folk psychology, which could be challenged. There is a quiet battle going on between philosophy and science. |
8871 | We should abandon a search for justification or foundations, and focus on how knowledge is acquired [Quine, by Davidson] |
Full Idea: Quine is suggesting that philosophy should abandon the attempt to provide a foundation for knowledge, or otherwise justify it, and should instead give an account of how knowledge is acquired. | |
From: report of Willard Quine (Epistemology Naturalized [1968]) by Donald Davidson - Epistemology Externalized p.193 | |
A reaction: If you are going to explain how 'knowledge' is acquired, you'd better know what knowledge is. My suspicion is that Quine would be quite happy (in the pragmatist tradition) to just focus on belief, and forget about knowledge entirely. |
8826 | If we abandon justification and normativity in epistemology, we must also abandon knowledge [Kim on Quine] |
Full Idea: Quine asks us to set aside the entire framework of justification-centered epistemology, ..and repudiate normativity. ..But then knowledge itself drops out of epistemology, for our concept of knowledge is inseparably tied to that of justification. | |
From: comment on Willard Quine (Epistemology Naturalized [1968]) by Jaegwon Kim - What is 'naturalized epistemology'? p.305 | |
A reaction: Presumably this would not bother Quine, who wants to hand so-called 'epistemology' over to the psychologists. A psychological account of belief seems plausible. Presumably false beliefs could only be pragmatically characterised. |
8827 | Without normativity, naturalized epistemology isn't even about beliefs [Kim on Quine] |
Full Idea: If normativity is wholly excluded from naturalized epistemology it cannot even be thought of as being about beliefs. | |
From: comment on Willard Quine (Epistemology Naturalized [1968]) by Jaegwon Kim - What is 'naturalized epistemology'? p.306 | |
A reaction: And if it doesn't refer to beliefs, it certainly doesn't refer to knowledge. One might try to subsume normativity under evolutionary pragmatic 'drives', or something. Quine's project would then become wildly speculative, and hence boring. |
8899 | Epistemology is a part of psychology, studying how our theories relate to our evidence [Quine] |
Full Idea: Epistemology falls into place as a chapter of psychology, and hence of natural science. ..We study meagre input and torrential output, to see how evidence relates to theory, and in what ways one's theory of nature transcends any available evidence. | |
From: Willard Quine (Epistemology Naturalized [1968], p.83) | |
A reaction: It depends what you are interested in. If you just want to know what makes humans tick, then Quine is your man, but if you want to know things in general, and want to know how to get it right, then the normative side of epistemology is unavoidable. |
13475 | The Fregean concept of GREEN is a function assigning true to green things, and false to the rest [Hart,WD] |
Full Idea: A Fregean concept is a function that assigns to each object a truth value. So instead of the colour green, the concept GREEN assigns truth to each green thing, but falsity to anything else. | |
From: William D. Hart (The Evolution of Logic [2010], 2) | |
A reaction: This would seem to immediately hit the renate/cordate problem, if there was a world in which all and only the green things happened to be square. How could Frege then distinguish the green from the square? Compare Idea 8245. |
23640 | Only mature minds can distinguish the qualities of a body [Reid] |
Full Idea: I think it requires some ripeness of understanding to distinguish the qualities of a body from the body; perhaps this distinction is not made by brutes, or by infants. | |
From: Thomas Reid (Essays on Intellectual Powers 2: Senses [1785], 19) | |
A reaction: I'm glad the brutes get a mention in his assessment of these questions. I take such thinking to arise from what can be labelled the faculty of abstraction, which presumably only appears in a mature brain. It is second-level thinking. |
8898 | Inculcations of meanings of words rests ultimately on sensory evidence [Quine] |
Full Idea: All inculcation of meanings of words must rest ultimately on sensory evidence. | |
From: Willard Quine (Epistemology Naturalized [1968], p.75) | |
A reaction: This betrays Quine's behaviourist tendencies, and rules out introspection, definitions and inferences. Quine's conclusion is fairly total scepticism about meaning, but that is not surprising, given his external and meaningless starting point. |
8900 | In observation sentences, we could substitute community acceptance for analyticity [Quine] |
Full Idea: Perhaps the controversial notion of analyticity can be dispensed with, in our definition of observation sentences, in favour of the straightforward attitude of community-wide acceptance. | |
From: Willard Quine (Epistemology Naturalized [1968], p.86) | |
A reaction: That might be a reasonable account of 'bachelors'. If the whole community accepts 'God exists', does that make it analytic? If a whole (small!) community claims to actually observe a ghost or a flying saucer, is that then analytic? |